Toxicity of Bacillus thuringiensis delta endotoxin is interrelated to larval midgut membrane receptor and its binding affinity and numbers.Binding to a specific receptor is an important determinant with respect to dif...Toxicity of Bacillus thuringiensis delta endotoxin is interrelated to larval midgut membrane receptor and its binding affinity and numbers.Binding to a specific receptor is an important determinant with respect to differences in insecticidal spectrum of Bacillus thuringiensis delta endotoxin.Membrane receptor has different binding sites which can interact specially with different binding determinants on the toxin molecules.Meanwhile,endotoxin might interact with more than one receptor in BBMV.The interaction of toxin and membrane receptor shows both the complexity and diversity,but not only recognizing one by one simply.Insect resistance to Bt is also related to the midgut membrane receptor in binding sites,affinity and numbers.It was shown that midgut membrane receptors are brush border membrane vesicles on the membrane of midgut epithelial cells,they belong to aminopeptidase family or cadherin family.Aminopeptidase acts as receptor just on its presence,but not its enzymatic activity.展开更多
Chromium(Cr) may cause losses in the yield of field plant, which is one of the favorite habitats of Bacillus thuringiensis(Bt). The purposes of our study were to assess the Cr(VI)-resistance and Cr(VI)-reducing abilit...Chromium(Cr) may cause losses in the yield of field plant, which is one of the favorite habitats of Bacillus thuringiensis(Bt). The purposes of our study were to assess the Cr(VI)-resistance and Cr(VI)-reducing abilities of an indigenous soil isolate of Bt and to determine the factors governing Cr(VI) reduction. Towards this end a novel dichromate-reducing Bt BRC-ZYR2, characterized with insecticidal crystal proteins(ICPs), was isolated from a uranium deposit. Minimum inhibitory concentrations(MICs) of Cr(VI) were determined by broth dilution method and the concentrations of Cr(VI) and total Cr in the supernatant were quantified colorimetrically using 1,5-diphenylcarbazide(DPC) reagent and a mixture of sulfuric-nitric acids, respectively. The isolate contained five ICP genes(cry1Ba, cry1 Bb, cry1Be/cry1 Bf, cry9 Ca and cry9Da) and exhibited a high level of Cr(VI) resistance with MICs of 150 mg L-1at pH 7.0 and 30?C, and 500 mg L-1under optimal conditions(pH 9.0 and 40?C). The total Cr concentration was similar to initial concentration of Cr(VI) under the optimal condition, suggesting that the essential removal of the Cr(VI) was dependent on Bt reduction. Under optimal conditions, the initial Cr(VI) concentrations from 25 to 75 mg L-1significantly decreased in 24 h after incubation. Addition of Mn2+, Co2+, Mo2+and Cu2+activated Bt-mediated Cr(VI) reduction, while Zn2+, Ni2+and glucose were found to inhibit the reduction. Our results indicated that this isolate could be a promising biopesticide with the potential for both insect biocontrol and Cr bioremediation in the field.展开更多
文摘Toxicity of Bacillus thuringiensis delta endotoxin is interrelated to larval midgut membrane receptor and its binding affinity and numbers.Binding to a specific receptor is an important determinant with respect to differences in insecticidal spectrum of Bacillus thuringiensis delta endotoxin.Membrane receptor has different binding sites which can interact specially with different binding determinants on the toxin molecules.Meanwhile,endotoxin might interact with more than one receptor in BBMV.The interaction of toxin and membrane receptor shows both the complexity and diversity,but not only recognizing one by one simply.Insect resistance to Bt is also related to the midgut membrane receptor in binding sites,affinity and numbers.It was shown that midgut membrane receptors are brush border membrane vesicles on the membrane of midgut epithelial cells,they belong to aminopeptidase family or cadherin family.Aminopeptidase acts as receptor just on its presence,but not its enzymatic activity.
基金Supported by the National Science and Technology Project in Rural Area during the"2th Five-Year Plan",China(Nos.2011AA10A203 and 2011BAD03B02-2)the National Natural Science Foundation of China(No.31201574)+3 种基金the Project of Fujian Provincial Department of Science and Technology,China(No.2011N5003)the State Key Laboratory for Biology of Plant Diseases and Insect Pests,Institute of Plant Protection,Chinese Academy of Agricultural Sciences(No.SKL2012OP05)the Talent Training Program for Distinguished Young Scholars in Universities of Fujian Province,China(No.JA12092)the Science Fund for Distinguished Young Scholars of Fujian Agriculture and Forestry University,China(No.xjq201203)
文摘Chromium(Cr) may cause losses in the yield of field plant, which is one of the favorite habitats of Bacillus thuringiensis(Bt). The purposes of our study were to assess the Cr(VI)-resistance and Cr(VI)-reducing abilities of an indigenous soil isolate of Bt and to determine the factors governing Cr(VI) reduction. Towards this end a novel dichromate-reducing Bt BRC-ZYR2, characterized with insecticidal crystal proteins(ICPs), was isolated from a uranium deposit. Minimum inhibitory concentrations(MICs) of Cr(VI) were determined by broth dilution method and the concentrations of Cr(VI) and total Cr in the supernatant were quantified colorimetrically using 1,5-diphenylcarbazide(DPC) reagent and a mixture of sulfuric-nitric acids, respectively. The isolate contained five ICP genes(cry1Ba, cry1 Bb, cry1Be/cry1 Bf, cry9 Ca and cry9Da) and exhibited a high level of Cr(VI) resistance with MICs of 150 mg L-1at pH 7.0 and 30?C, and 500 mg L-1under optimal conditions(pH 9.0 and 40?C). The total Cr concentration was similar to initial concentration of Cr(VI) under the optimal condition, suggesting that the essential removal of the Cr(VI) was dependent on Bt reduction. Under optimal conditions, the initial Cr(VI) concentrations from 25 to 75 mg L-1significantly decreased in 24 h after incubation. Addition of Mn2+, Co2+, Mo2+and Cu2+activated Bt-mediated Cr(VI) reduction, while Zn2+, Ni2+and glucose were found to inhibit the reduction. Our results indicated that this isolate could be a promising biopesticide with the potential for both insect biocontrol and Cr bioremediation in the field.
